How to kill a session after logging out using php

Question

I have seen the following question and tried to adapt part of the answer but to no luck: \'How can i disable the back browser button after user press logout and destroy session?

Answer 1

As for headers, here are the ones from a web server I regularly use after a search:

Cache-Control: private, pre-check=0, post-check=0, max-age=0
Expires: 0
Pragma: no-cache

Pressing the back button after clicking a link from the results page displays an error message in Firefox. The only notable difference I see is Expire: 0.

Answer 2

login page:

<?php 
if (isset($_POST['uname'], $_POST['pwd'], $_POST['type'])) {
    $Username = $_POST['uname'];
    $Password = $_POST['pwd'];
    $User_Type=$_POST['type'];
    if (!(empty($Username) || empty($Password) || empty($User_Type))) 
    {
         $model = new UsersModel();
         $rowsCount = $model->checkUser($Username,$Password,$User_Type);
         if ($rowsCount!=0)
         {
              $_SESSION['user'] = $Username;
              header("Location:LoginViewController.php");

         } else {
              echo 'Bad user';
         }
    } else {
         echo 'Please, fill all inputs';
    }
} else {
    echo 'Bad form sent';
}
?>
 <form name="f1" method="POST" action="" >
// inputs
 </form>

LoginViewController.php :

<?php
header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
header("Expires: Sat, 26 Jul 1997 05:00:00 GMT");

if (!isset($_SESSION['user'])) {
header('Location: login.php');
exit();
}
echo 'You have successfully logged as '.$_SESSION['user']
?>

And add the headers to force the browser to revalidate the pages :

logout.php :

<?php 
session_start();
session_destroy();
$_SESSION = array();
header("location: login.php");
?>